Method for assembling a weather-protecting roof truss and a weather-protecting roof truss bundle

ABSTRACT

Disclosed is a method for the installation of a roof truss on an upper part of a building. A roof truss package includes multiple trusses spaced from each other to be mounted on top of upper runners on the building&#39;s opposite walls. The method includes using a prefabricated roof truss package in which the individual trusses are disposed side by side in a bundle, with weather protection present in a pleated condition on top of the bundle. The bundle is unfolded at construction site in such a way that the adjacent trusses become locked at a certain distance from each other by brace members included in the trusses and at the same time the weather protection unfolds to cover the trusses and the intervening space. Finally, the individual trusses are fastened to the upper runners. Also disclosed is a prefabricated roof truss package which is provided with a weather protection.

The present invention relates to a method as set forth in the preamble of claim 1 for the installation of a weather-protective roof truss, and to a weather-protective roof truss package as set forth in the preamble of claim 4.

When building new detached houses and row houses, one major problem is how to provide weather protection for the structures in a sufficiently early stage. When the house is constructed from prefabricated elements in a conventional manner, the erection of wall elements takes about half a day and, thus, there won't be enough time during the rest of the day for the installation of a roof for weather protection as this may take even several days. This may lead to water damage, and thereby to mold problems which have been quite common in recent times. In addition, the installation of roof trusses according to current building practice is demanding in terms of occupational safety as it requires a fair amount of climbing up and down the roof. The installation work is also quite a slow process.

The invention described in this patent application relates to a solution comprehensively more efficient than the current practice and prior known technology for the installation of roof trusses, roof sheathing and gable elements.

Making use of the invention enables, remarkably more rapidly and efficiently than before, the installation of a weather protection in conjunction with the construction of permanent roof structures for buildings (such as for example all small houses or single-family houses: a detached house, a row house, a leisure time house, and the like), which at the same time improves substantially the safety of roofing jobs, pre-empts water damage occurrences during construction, and allows for roofing jobs also in varying climate conditions. After the installation of a solution according to the present invention, the construction jobs can be continued as usual, for example by the installation of roof battens and coverings.

It is an objective of the present invention to provide an improved method for the installation of a weather-protective roof truss. In order to attain this objective, a method according to the invention is characterized in that the method comprises using a prefabricated roof truss package in which the individual trusses are disposed side by side for a bundle and previously provided with a weather protection present in a pleated condition on top of the truss bundle; unfolding the bundle at construction site in such a way that the adjacent trusses become locked at a certain distance from each other by means of brace members included in the trusses and at the same time the weather protection unfolds to cover the trusses and the intervening space, and finally fastening the individual trusses by outer edges thereof to the upper runners. On the other hand, a roof truss package according to the invention is characterized in that the roof truss package is provided at a manufacturing plant with a weather protection which is attached to the trusses, that the roof truss package has its trusses arranged for a bundle in which the weather protection is in a pleated condition, and that the trusses are provided with brace members capable of locking the adjacent trusses at a certain distance from each other as the bundle is unfolded. In the context of this application, weather protection is a term used generally in reference to any type of structure or material affording protection against the weather and also functioning at the same time as roof sheathing and/or condensation sheathing for a roof structure to be subsequently completed. The material for the trusses is preferably wood, but the invention is not limited solely to timber-based trusses.

Making use of the invention enables, remarkably more rapidly and efficiently than before, the installation of a weather protection along with the construction of permanent roof structures for buildings (such as for example all small houses or single-family houses: a detached house, a row house, a leisure time house, and the like), which at the same time improves substantially the safety of roofing jobs, pre-empts water damage occurrences during construction, and allows for roofing jobs also in varying climate conditions. After the installation of a solution according to the present invention, the construction projects can be continued as usual, for example by the installation of roof battens and coverings.

The solution according to the invention allows for the manufacture and rapid installation of a prefabricated weather-protective robust roof truss. In comparison with the conventional installation of roof trusses, the solution according to the invention provides a considerable time saving, even up to about 90% faster installation, in the installation of a weather-protective roof, and an improvement in occupational safety with lesser demand for climbing. The installation of roof structures in a weather-protective manner as set forth in the invention can be carried out even in just roughly 1-2 hours. The mold problems caused in the structures by moistures during construction will be substantially mitigated. The quality of roof building in conventional construction work is dependent on the builder's skills while, when using the solution of the invention, the workmanship remains at high standard and consistent regardless of a person doing the work.

The invention cuts back substantially the total completion time of a building as it reduces the roof building time and allows for an earlier commencement of interior jobs. In addition, the invention provides savings in materials and transportations and overall costs.

The invention set forth in the patent application offers numerous advantages over prior known technology, a few of which will be discussed briefly as follows.

Utilization of Commercially Available Standard Components

The invention as presented in the patent application, “a solution for the installation of a roof truss”, comprises “a weather protection bundle” which in turn comprises roof trusses, a roof sheathing, and gable elements as an assembly that can be produced industrially, in controlled conditions, and in a material efficient manner.

The working of “a weather protection bundle” is made possible by innovative, if desired recyclable components and solutions which enable an operation according to the invention by using commercially available components as trusses, a roof sheathing and gable elements. Therefore, the question is about a comprehensive invention making use of the entire industry, which differs from all prior known techniques in the sense that the weather protection during construction time is achieved without supplementary structures (e.g. a tent around the building or other structures necessary for establishing weather protection and not a permanent part of the house under construction), thereby incurring extra costs.

The fact that the weather protection problem has not yet been resolved in the industry can be considered to stem from prior known solutions being liable to increase labor and material costs. This practical fact demonstrates strongly the innovative quality of the invention presented herein.

Reduction of Water Damage Occurrences During Construction

A major risk in construction are mold damage occurrences. Mold and water damage occurrences constitute a significant problem in terms of national economy. Most of the mold damage occurrences stem from exposure to moisture during construction work. In practice, the water damage occurrences in exterior structures develop most frequently in conditions wherein the structures (such as walls) are exposed to moisture before other permanent structures (such as the roof) have been put in place.

Therefore, in conditions with the air containing moisture and/or the weather conditions otherwise fluctuating for example in various seasons, the construction time is without specific measures usually restricted to seasons that enable installation projects to be conducted with a minimum risk of damaging the structures during construction. In practice, this entails that for example roofing jobs are limited to a minimum, among other things, when it is raining or snowing, because the structures do not withstand rains to significant extent. As roofing jobs occupy a central role in the house building project, other construction work of the building will be delayed respectively as long as the roofing jobs cannot be carried out and the structures thereby protected from elements (in other words be “weather-protected”). Accordingly, for example in Finland and in numerous other countries where conditions are not rainless and warm throughout the year, the effective and safe construction seasons for buildings is restricted to just a few months of the year.

The climate-imposed limitations on a construction season lead to major challenges both for individual builders and developers and more extensively for construction industry. Due to these limitations, construction is not only slow but the effects extend also, among others, to the productivity of construction sector and the jobs available for construction workers.

At the request of Ministry of the Environment and by working with universities, the construction industry has for a long time endeavored to create a standard that would define measures during construction for preventing these water damage occurrences in construction time (a so-called “weather protection standard”). An objective of the weather protection standard is to ensure for the structures such a protection during construction that water damage cases and resulting major financial and health-related setbacks shall not take place. Even despite years of efforts by the authorities, a solution to the weather protection problem has not been found prior to coming up with the present invention.

The currently employed methods are based on protecting a building with a sheathing separate from the building, such as for example by constructing “a tent” upon the building for the duration of construction. Such a solution is loose from the actual structures and it must be constructed separately for protecting the building. The construction of a separate protective sheathing postpones the commencement of construction works as well as increases construction costs substantially. In the event of using “a tent”, the construction of a separate protective sheathing is followed by the actual roof building work with conventional methods on a conventional schedule. On the other hand, with the invention according to this patent application, the weather protection can be established without separate procedures (and without putting on separate tarps) along with the ongoing installation of roof trusses. Since the installation of roof trusses can be conducted with the present invention on average even up to 90% faster than with traditional methods, the structures will be provided with weather protection considerably sooner and, therefore, the risk of water damage occurrences is remarkably mitigated. With the invention presented in the patent application, weather protection during construction is accomplished considerably faster and more cost effectively than with the prior known competing method (a separate “tent”/tarp system). When utilizing the present invention, the installation of roof trusses can be followed by proceeding faster to the finishing installation of battens and roof surface materials, whereby the final completed roof structure and hence a protection for the building in its final condition is also achieved faster. The present invention also allows for a certification of the construction method in a manner that enables the rapid installation of weather protection to be documented for a client who has ordered the house. This is another aspect that promotes construction quality as well as customer safety.

Because the invention presented in the patent application enables roof trusses and weather protection to be installed considerably faster than what has been known before, there will be significant advantages gained over prior known technology.

Improvement of Occupational Safety

As already pointed out above, the present invention has an objective of providing an improved method for the installation of roof structures, a weather-protective roof truss, as well as providing an innovative roof truss package the utilization of which enables the foregoing objectives to be attained. In addition to the fact that the invention according to this patent application reduces remarkably the hazard of water damage incidents during construction, expedites the installation of a roof, as well as the building construction work to continue in various weather conditions, the invention according to this patent application can also be used for significantly improving the safety of building construction work.

When compared to other industries, it is the construction sector where most occupational accidents take place in Finland. The annual number of occupational accidents in construction industry is about 17000-19000—the occupational accident incidence rate in construction industry is about twice as high as in the next most accident-prone sector.

Within construction industry, more frequently than in others occupational accidents occur in building construction sector with the risk of an occupational accident in the latter being 2-4 times higher compared to other industries. The most typical workplace accidents in construction industry include falls, slips, jumps and trips. Construction industry is also where most fatal workplace accidents occur. The most common cause of fatal workplace accidents in construction industry is a fall from height.

In building construction industry, the risk of workplace accident is particularly pronounced in roof work. Roof working jobs involve particularly a risk of falling from height, which is why the fall protections for roof work sites are specifically regulated in the Council of State Ordinance on the safety of construction work. Hence, measures mitigating the hazardousness of roof jobs are profoundly meaningful in construction industry.

Making use of the invention according to this patent application renders it possible to reduce significantly the time spent for roof jobs, to reduce the amount of high-risk roof work, to expedite and promote safety measures needed for the finishing touches of a roof, and thereby to improve comprehensively the safety of roof construction jobs.

First of all, the traditional installation of roof trusses is highly time-consuming work the fulfillment of which is, as presented above, dependent on weather conditions. On the other hand, both the installation of roof trusses with a method of this patent application and the use of a roof truss package according to this patent application render the installation of roof trusses significantly faster with respect to traditional methods: With the invention set forth in the present application, the installation of roof trusses can be successfully performed as much as about 90% faster than with techniques known prior to the invention. Just the significant reduction in the installation time of roof structures alone brings about respectively a significant reduction in the probability of occupational accident occurrences.

Secondly, with traditional solutions, the roof truss is installed from outside the building manually regardless of whether or not the above-discussed “tent” is used as a weather protection. When using traditional techniques, the installation of roof trusses from outside nevertheless requires very hazardous climbing movements on top of the roof trusses undergoing installation. In addition, the installation of roof trusses from outside necessitates the installation and use of hoists and scaffolds, which is time consuming, expensive and likewise involves risks from the standpoint of occupational safety. Instead, the method according to the invention for the installation of roof truss can be carried out from inside the building manually after the roof truss package has been placed at one of the gables of the house or at some other starting point. Consequently, making use of the invention according to this patent application renders it possible to reduce significantly the risks of workplace accidents in the installation process of roof trusses since the installation, as opposed to traditional techniques, does not require hazardous climbing movements on top of the roof trusses.

Thirdly, after the completion of a roof sheathing, the roof construction work progresses conventionally to roof finishing work such as, among others, the installation of battens and roof surface materials. This work necessitates setting up safety rails and other safety equipment, which in its part increases occupational safety risks. When using the invention according to this patent application, the roof truss bundles can be pre-fitted at the factory with safety rails needed for the installation of a roofing (such as for example battens and metal roofing, clay tile roofing or other roofing). This both expedites the installation of roofing and improves remarkably occupational safety as the safety features need not be installed on site for the roof finishing work.

The roof work reducing, roof work nature changing, as well as use-of-safety features facilitating effect of the present invention, and the occupational safety improving substantially as a result thereof, constitutes in and of itself a highly significant innovation and a remarkable improvement with respect to the prior art and its longstanding problems.

The invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 shows one roof truss package for use in a method of the invention at a commencement stage of installation,

FIG. 2 shows the roof truss package of FIG. 1 in a partially installed condition,

FIGS. 3a, 3b show one detail in a roof truss of the invention, and

FIG. 4 shows a roof truss of the invention in an isometric view.

In the process of installing a roof truss, it is a roof truss package in the form of a bundle which is lifted with a hoist onto the roof and placed at one gable of the house or at some other desired starting point and braced to an upright position from an outermost truss 3. In the exemplary case shown in FIG. 1, a bundle 1 has been hoisted to the upper part of a building onto top runners 6 of the building's opposite walls 7 at one gable of the building. The top runners are mounted to rest on load-bearing upright posts of the walls.

FIG. 1 shows also one exemplary embodiment of a roof gable element, which comprises an eaves section 12 and a gable wall section 13, said gable element having been preferably pre-fitted at the factory to the attachment with the roof truss at both ends thereof. Prefabrication in this context refers to manufacturing conducted in a factory building or the like sheltered space irrespective of whether the production is automated or mechanized or manually conducted production. The eaves section 12 comprises fascia boards 18 and soffit boards 19. The gable wall section 13 includes studwork 14, which is fastened to an outermost truss 3 of the bundle 1 and to which is fastened a wind protection slab 15. On top of the wind protection slab is mounted studwork 16 with exterior wall panels 17 fastened thereto.

After this, the bundle is unfolded by moving it with the assistance of an installation cradle (not shown) along the roof, the bundle releasing one truss at a time. FIG. 2 shows a bundle in a partially unfolded condition. The unfolding can be conducted e.g. by means of a winch or a hoist. Preferably, the installation is conducted from inside the building by using a remote controller for manipulating the winches which operate the installation cradle. The trusses are fitted with lower brace member 4 and upper brace members 5 capable of locking the trusses at a predetermined distance from each other to provide a previously supported structure, wherein individual trusses, except for the first truss, need not be separately supported on the building frame structures. The number of each of the brace members 4 and 5 is at least two per truss.

FIGS. 3a, 3b show one preferred embodiment of the lower brace members 4 more closely in schematic views of principle. FIG. 3a depicts a starting condition, and FIG. 3b shows a condition in which a truss 3′ next to the gable truss 3 has been removed from the gable truss to a distance defined by the brace member 4. In the presented exemplary embodiment, the brace member 4 consists of a two-component support, having first and second support arms 4 a, 4 b which are pivotally connected at one end thereof to the trusses 3 and 3′, respectively, and at the other end thereof to each other with an articulated joint 4 c capable of locking the support arms to each other while defining a distance between the trusses 3, 3′. The upper brace members 5 are designed similarly as a two-component unit. The number of brace members 4 and 5 is typically 4-6 in each inter-truss space. The brace members are preferably accompanied by clamping elements which keep the truss bundle intact and, upon unclamping, release the brace members of the next inter-truss space to unfold as the truss bundle is advanced. The material for the brace members can be e.g. metal, plastics or wood or various combinations thereof.

After unfolding, the trusses are attached by outer edges thereof with fastening means to upper runners 6 for preventing the wind from jerking the truss bundle off from top of the upper runners. The fastening means may comprise e.g. an angle bar or the like. The roof truss bundle is previously equipped at the factory with a weather protection 2, which is in a pleated condition on top of the bundle 1 and in attachment with the trusses, such that, as the bundle is being unfolded, the weather protection straightens out to cover the space between adjacent trusses. Once the bundle has been completely unfolded, the roof is immediately in a weather protected condition. The weather protection can have two or more layers, thereby facilitating the use of new materials more advanced in terms of their absorption/breathability or insulating properties.

Alternatively, a roof truss of the invention can be previously unfolded even on the platform of a transport vehicle, on retractable rails or on the ground, and then hoisted onto the roof, whereby all that is necessary to do on the roof is to fasten the trusses to the upper runners.

FIG. 4 shows in a schematic isometric view a roof truss in a partially unfolded condition. The weather protection 2 is in this example fastened to individual trusses by means of ventilation ribs 11. The weather protection is provided separately on both slopes of the roof for enabling the pleating thereof for transport. On top of the ventilation ribs 11 at the roof apex will be provided a separate weather protection strip (not shown), which enables effective ventilation in a completed roof structure and protects a ventilation gap of the weather protection 2 developing at the apex. The strip can be previously mounted on top of the ventilation ribs 11 of the weather protection 2 on one of the slopes to facilitate its installation while the roof truss is in a completely unfolded condition. 

1. A method for the installation of a roof truss on an upper part of a building, said roof truss comprising a plurality of trusses (3) spaced from each other to be mounted on top of upper runners (6) present in an upper part of the building's opposite walls, said roof truss working as a roof sheathing, characterized in that the method comprises using a prefabricated roof truss package in which the individual trusses (3) are disposed side by side for a bundle (1) and previously provided with a weather protection (2) present in a pleated condition on top of the truss bundle; unfolding the bundle (1) at construction site in such a way that the adjacent trusses (3) become locked at a certain distance from each other by means of brace members (4, 5) included in the trusses and at the same time the weather protection (2) unfolds to cover the trusses and the intervening space, and finally fastening the individual trusses by outer edges thereof to the upper runners (6).
 2. A method according to claim 1, characterized in that it comprises initially hoisting the bundle (1) onto the roof and propping it to an upright position at a desired installation point from which its unfolding along the upper runners (6) is commenced.
 3. A method according to claim 1, characterized in that it comprises unfolding the bundle (1) previously and locking the trusses (3) at a certain distance from each other and then hoisting the same as a completed roof truss onto the roof and fastening the same to the upper runners (6).
 4. A roof truss package, comprising a plurality of trusses (3) which are spaced from each other and adapted to be mounted on top of upper runners (6) present in an upper part of the opposite walls of a building, and said trusses work in such an installed condition as a roof sheathing, characterized in that the roof truss package is provided at a manufacturing plant with a weather protection (2) which is attached to the trusses (3), that the roof truss package has its trusses (3) arranged for a bundle (1) in which the weather protection (2) is in a pleated condition, and that the trusses (3) are provided with brace members (4, 5) capable of locking the adjacent trusses (3) at a certain distance from each other as the bundle is unfolded. 